ci: run e2e smoke against deployed app and ignore playwright artifacts

- Add e2e job (needs deploy, main/master only) that installs the
  Playwright browser and smoke-tests the live container on :3002
- Keep deploy-job contract slice from bleeding into the e2e job
- Cover the e2e job in the CI workflow contract test
- Ignore Playwright output dirs (test-results, playwright-report,
  blob-report)

.gitignore

@@ -33,4 +33,9 @@ public/tmp/
 
 # Test coverage reports
 coverage/
+
+# Playwright test artifacts
+test-results/
+playwright-report/
+blob-report/
 .aider*